Wheezing and Asthma
- Definition: Continuous high-pitched sound with musical quality emitting from the chest during expiration.
- Patterns of wheezing (J Allergy Clin Immunol 2003;111(4):661): According to the Tucson children’s respiratory study, a child who begins wheezing in the early years of life (<3 yr) can be classified into one of the following three phenotypes:
-
Transient early wheezing (not associated with eczema, other atopy, or family hx of asthma)
- Comprises 80% of children who wheeze during the first year of life and 60% of children during second year of life.
- Wheezing episodes resolve by age 3 yr.
- Risk factors include low infant pulmonary function, maternal smoking during pregnancy, younger mother.
-
Non-atopic wheezing
- Children who continue to wheeze beyond the third year of life after having an RSV or other viral LRI early in life.
- RSV-LRI predisposes to lower lung function and more likely bronchodilator response.
-
IgE-associated or atopic wheeze or asthma
- Episodes more likely to continue beyond age 6 yr.
- Associated with markers of atopy (high IgE, eosinophilia).
- Family hx of asthma (especially in the mother), increased other atopy (eczema, rhinitis).
- Lowest lung function at age 6 yr compared with other phenotypes.
-
- Differential diagnosis: Modified asthma predictive index (API; J Allergy Clin Immunol 2004;114(6):1282): Identifies children with wheezing who are at risk for persistent asthma; requires h/o four or more episodes of childhood wheezing and one major and two minor criteria
- See table below
Differential Diagnosis for a Child with Wheezing
|
Age <5 Years |
Age >5 Years |
|---|---|
|
|
Modified Asthma Predictive Index
|
Major Criteria |
Minor Criteria |
|---|---|
|
Parental history of asthma Physician-diagnosed atopic dermatitis Allergic sensitization to at least one aeroallergen |
Allergic sensitization to eggs, milk, or peanuts Wheezing apart from viral illness Blood eosinophilia >4% |
- Definition: Chronic inflammatory disorder of the airways associated with airway hyperresponsiveness that leads to recurrent episodes of combinations of wheezing, breathlessness, chest tightness, or coughing. Usually associated with diffuse but variable airflow obstruction within the lung that is often reversible spontaneously or with treatment.
- Pathophysiology: Combination of bronchial smooth muscle constriction and obstruction of the lumen (by inflammatory exudates and airway wall edema).
Clinical History and Physical Exam for Diagnosing Asthma
|
History |
Physical Exam |
|---|---|
|
|
- Diagnostic studies
- CXR: May be normal or may show hyperinflation (flattened diaphragm chest A/P diameter) or peribronchial thickening.
- Peak flow monitors: May be useful in children ≥6 yr, especially those with poor symptom perception. Used to assess the severity of exacerbations, monitor response to therapy (compare with personal best at baseline or can estimate goal PEF using predicted table by gender, height, age). Limitations include that it is effort dependent and requires training (can have false high and low values).
- Spirometry: Obstructive pattern with ↓ FEV1 and ↓ FEV1/FVC ratio; scooped or concave pattern on expiratory flow–volume loop.
- Positive bronchodilator (BD) response = ↑ of ≥12% in FEV1 after inhaled short-acting □-agonist.
- Bronchial provocation tests: May use exercise, histamine, or methacholine to provoke airway hyperresponsiveness with recovery post-BD.
- Management: There are four components to asthma management (NAEPP EPR-3, 2007, http://www.nhlbi.nih.gov.easyaccess2.lib.cuhk.edu.hk/guidelines/asthma):
- Component 1: Asthma assessment (see table below) and objective monitoring (see table “Assessing control and adjusting therapy”)
- Component 2: Education for a partnership in asthma care
- Train families in self-management skills, including monitoring, treatment, and communication.
- Define goals for good asthma control. Goals should include (1) control symptoms, allowing normal levels of activity and undisturbed sleep; (2) prevent exacerbations; (3) maintain normal lung function; and (4) use minimal therapy necessary to minimize side effects.
- Provide a written asthma action (management) plan and emergency information.
- Printable asthma action plan template: NHLBI EPR3, page 402 (http://www.nhlbi.nih.gov.easyaccess2.lib.cuhk.edu.hk/guidelines/asthma/asthgdln.pdf)
- Printable MDI instructions: NHLBI EPR3, page 403(http://www.nhlbi.nih.gov.easyaccess2.lib.cuhk.edu.hk/guidelines/asthma/asthgdln.pdf)
- Component 3: Control of environmental factors and comorbid conditions that affect asthma
- Define specific allergy sensitization (skin testing or RAST/ImmunoCap) and avoid exposure; consider immunotherapy.
- Eliminate exposure to active or passive tobacco smoke; limit exposure to air pollutants.
- Manage comorbid conditions (GERD, allergic rhinitis).
- Annual influenza vaccine, good handwashing.
- Component 4: Pharmacologic therapy
- All patients need access to quick-relief bronchodilator (short-acting β2-agonist).
- Daily controller therapy based on severity and control; consider both impairment and risk (See tables “Medications commonly used for treating Asthma” and “Stepwise approach to management of Asthma” below).
- Inhaled drug delivery technique is important to avoid frequent errors; check regularly.
- MDI with a spacer has similar or better efficacy, more portability and a shorter administration time compared to a nebulizer.
- Spacer (valved holding chamber) with MDI improves lower airway delivery at all ages (including adults) and reduces side effects (thrush with ICS).
Classifying Asthma Severity and Initiating Therapy*
|
Components of severity |
Intermittent |
Persistent | |||
|---|---|---|---|---|---|
|
Mild |
Moderate |
Severe | |||
|
Impairment |
Symptoms |
≤ 2 days/wk |
>2 days/ wk |
Daily |
Throughout the day |
|
Nighttime awakenings |
0-4 yr: 0 ≥5 yr: ≤ 2x/mo |
0-4 yr: 1-2x/mo ≥5 yr: 3-4x/mo |
0-4 yr: 3-4x/mo ≥5 yr: >1x/wk |
0-4: >1x/wk ≥5 yr: Often, 7x/wk | |
|
SABA use for symptoms |
≤2 days/wk |
>2 days/wk |
Daily |
Several times per day | |
|
Interference with normal activity |
None |
Minor |
Some |
Extreme | |
|
Lung function |
Normal FEV1 between exacerbations FEV1 >80% predicted 5-12 yr: FEV1/FVC >85% ≥12 yr: FEV1/FVC normal |
FEV1 >80% predicted 5-12 yr: FEV1/FVC >80% ≥12 yr: FEV1/FVC normal |
FEV1: 60%-80% predicted 5-12 yr: FEV1/FVC 75%-80% ≥12 yr: FEV1/FVC reduced 5% |
FEV1 < 60% predicted 5-12 yr: FEV1/FVC< 75% ≥12 yr: FEV1/FVC reduced >5% | |
|
Risk |
Exacerbations requiring oral corticosteroid |
0-1/yr |
0-4 yr: ≥2 in 6 mo OR ≥4 wheezing episodes per 1 year lasting >1 day ≥5 yr: ≥2/yr | ||
|
Recommended Initial Therapy (see table “Stepwise approach to management of asthma” below) |
Step 1 |
Step 2 |
Step 3 |
0-4 yr: Step 3 5-12 yr: Step 3 or 4 ≥12 yr: Step 4 or 5 | |
|
and consider short course of oral systemic steroids | |||||
|
In 2-6 weeks, evaluate level of asthma control and adjust therapy accordingly. | |||||
Assessing Control and Adjusting Therapy*
|
Components of Severity |
Well Controlled |
Not Well Controlled |
Very Poorly Controlled | |
|---|---|---|---|---|
|
Impairment |
Symptoms |
≤2 d/wk |
>2 d/wk |
Throughout the day |
|
Nighttime awakenings |
0–11 yr: ≤1x/mo ≥12 yr: ≤2x/mo |
0–11 yr: ≥2x/mo ≥12 yr: 1–3x/wk |
0–11 yr: ≥2x/wk ≥12 yr: ≥4x/wk | |
|
Interference with normal activity |
None |
Some limitation |
Extremely limited | |
|
SABA use for symptoms |
≤2 days/wk |
>2 days/wk |
Several times per day | |
|
Lung function FEV1 or peak flow FEV1/FVC (> = 5 yr) |
>80% predicted or personal best >80% |
60%–80% predicted or personal best 75%–80% |
<60% predicted or personal best <75% | |
|
Risk |
Exacerbations requiring oral corticosteroids |
0–1x/yr |
<5yr: 2–3x/yr ≥5yr: ≥2x/yr |
<5 yr: >3x/yr ≥5 yr: ≥2x/yr |
|
Treatment-related adverse effects |
Medication side effects do not correlate with specific levels of control but should be considered in the overall assessment of risk | |||
|
Recommended Action for Treatment |
Maintain current step Regular follow-up q 1-6 mo Consider stepdown if well controlled for ≥3 mo |
Step up 1 step and reevaluate in 2–6 wk |
Consider short course of oral corticosteroid Step up 1–2 steps and reevaluate in 2 wk | |
|
For side effects, consider alternative treatment options | ||||
Medications Commonly Used for Treating Asthma
|
Medication Class |
Examples |
Adverse Effects |
Comments |
|---|---|---|---|
|
Short-acting β-agonist (SABA) |
Albuterol Levalbuterol |
Tachycardia, nervousness, tremors |
Short-term symptom relief and pre-exercise |
|
Systemic corticosteroid |
Prednisolone Prednisone Methylprednisolone Dexamethasone |
Altered behavior, nausea or vomiting, pituitary adrenal axis suppression (long-term therapy) |
Short courses are effective for exacerbations or establishing control at initiation of therapy High-dose or extended therapy should be weaned as tolerated |
|
Inhaled corticosteroid (ICS) |
MDI: Fluticasone, beclomethasone, flunisolide, triamcinolone DPI: Budesonide, mometasone Nebulized: Budesonide |
Thrush Decreased height velocity* (temporary) Adrenal suppression (high dose) |
Mainstay of preventive therapy Different ICS have similar efficacy but different potency High-dose therapy should be weaned |
|
ICS + long-acting β2-agonist (LABAs) |
Fluticasone + salmeterol Budesonide + formoterol |
As above for ICS, Headache |
FDA alert: LABAs should not be used for symptom relief or without concomitant ICS |
|
Leukotriene receptor antagonist |
Montelukast Zafirlukast |
Headache, nausea, cough |
FDA alert: Rarely neuropsychiatric events have been reported. Also used for allergic rhinitis |
|
Anti-IgE monoclonal antibody |
Omalizumab |
Injection site reaction Anaphylaxis |
For use in persistent allergic asthma refractory to high-dose ICS |
Stepwise Approach to Management of Asthma*†
|
Preferred Treatment | |
|---|---|
|
Step 1 |
SABA PRN |
|
Step 2 |
Low-dose inhaled corticosteroid (ICS) |
|
Step 3‡ |
0–4 yr: Medium-dose ICS 5–11 yr: Low-dose ICS + either LABA, LTRA, or theophylline; OR medium- dose ICS ≥12 yr: Low-dose ICS + LABA; or medium-dose ICS |
|
Step 4‡ |
0–4 yr: Medium-dose ICS + either LABA or montelukast ≥5 yr: Medium-dose ICS + LABA |
|
Step 5‡ |
0–4 yr: High-dose ICS + either LABA or montelukast ≥5 yr: High-dose ICS + LABA (consider omalizumab for patients ≥12 yr with allergies) |
|
Step 6‡ |
0–4 yr: High-dose ICS + either LABA or montelukast + oral systemic steroid ≥5 yr: High-dose ICS + LABA + oral systemic steroid (consider omalizumab for patients ≥12 yr with allergies) |
Cystic Fibrosis
- Epidemiology: 30,000 patients in the US; incidence of CF in US by racial or ethnic group: Caucasians, one in 2500; Hispanics, one in 8500; African Americans, one in 15,000; Asian Americans, one in 31,000.
- Genetics
- AR transmission; defect in a single gene on chromosome 7 that encodes a chloride channel called the cystic fibrosis transmembrane regulator (CFTR).
- The ΔF508 mutation is the most common mutation, present in ∼70% of CF alleles in the US; however, >1500 CFTR mutations have been identified.
- Diagnosis: CF is a clinical diagnosis that requires laboratory corroboration.
Criteria for the Diagnosis of Cystic Fibrosis
|
Plus |
Evidence of abnormal CFTR function as demonstrated by one of the following:
|
- Sweat chloride test: Pilocarpine iontophoresis is the gold standard for CF diagnosis but is not always conclusive (see table “Reference values for sweat chloride test” below). Sweat test can be done starting at age 2 weeks.
- Sequencing of all known CFTR DNA mutations can identify 90% of CF mutations.
- Sweat chloride levels and genotype analysis cannot be used to predict prognosis.
- Newborn screen (NBS) can identify newborns at risk for CF. NBS protocols for screening vary by state, but all NBS identify blood level of immunoreactive trypsinogen (IRT).
- First NBS ⊕ → Refer to a CF center for repeat testing. Testing is based on your state’s NBS program (IRT testing repeat, sweat test, CF DNA mutation analysis or a combination of these tests).
- The panel of CF DNA mutations analyzed varies by state, therefore this test can miss rare mutations. If a patient has borderline sweat test and/or clinical suspicion for CF then sequencing of all known CFTR DNA mutations should be performed.
- First NBS ⊕ → Refer to a CF center for repeat testing. Testing is based on your state’s NBS program (IRT testing repeat, sweat test, CF DNA mutation analysis or a combination of these tests).
Reference Values for Qualitative Pilocarpine Iontophoresis Sweat Chloride Test*
|
Normal (CF Unlikely) |
Indeterminate** |
Abnormal (CF Likely) | |
|---|---|---|---|
|
Infants <6 mo |
≤29 mmol/L |
30–59 mmol/L |
≥60 mmol/L |
|
≥6 mo |
≤39 mmol/L |
40–59 mmol/L |
≥60 mmol/L |
Common Symptoms and Signs of Cystic Fibrosis in Various Age Groups
|
Infancy |
Childhood |
Adolescence and Adulthood |
|---|---|---|
|
Meconium ileus Obstructive jaundice Failure to thrive Hyponatremic dehydration or metabolic alkalosis Edema with hypoproteinemia and anemia Rectal prolapse Recurrent pneumonia or bronchiolitis Salty-tasting skin Acute salt depletion Chronic metabolic alkalosis |
Failure to thrive Steatorrhea Distal intestinal obstruction Chronic sinopulmonary disease Recurrent pneumonia Chronic cough and sputum “Atypical” asthma with bronchiectasis, clubbing Persistent CXR abnormalities Pansinusitis Nasal polyps Symptoms of vitamin A, D, E, or K deficiency Heat prostration with hypoelectrolytemia |
Delayed sexual development Obstructive azoospermia or infertility Congenital absence of the vas deferens Chronic bronchitis with Pseudomonas aeruginosa Bronchiectasis or clubbing Pansinusitis Chronic abdominal pain Idiopathic pancreatitis Cirrhosis Distal intestinal obstruction Diabetes mellitus Hemoptysis Pneumothorax |
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